1 Is Fidelity in any financial trouble? Hardly. With $1.4 trillion in assets under management, the privately held firm is a fee-generating machine. In the lucrative 401(k) market, its 24% share makes it the No. 1 player. In its February report, Moody's reaffirmed its excellent Aa3 rating on the money manager's debt—although it did change its outlook to "negative."

2 So what is Moody's concerned about? The ratings agency cited "competitive threats to the company's leading share of the mutual fund market" and its narrowing advantage as competition heats up for trillions in baby-boomers' rollover assets. According to Morningstar, Fidelity's market share in equity funds fell from 18.1% in 1995 to 12.5% in 2006.

3 What about the executive who just left? In January the executive director of Fido's money-management unit, Stephen Jonas, announced his exit after just 20 months. But Jim Lowell of newsletter Fidelity Investor describes it as a routine change. The bigger issue is what happens when chairman Ned Johnson (above) steps down. "That," Lowell says, "will impact investors."

4 What does Fidelity say? A spokeswoman says Fido is confident about its ability to grow and attract boomers, citing the "breadth of our reach"—from the firm's dominant position in the 401(k) business to its nationwide network of 114 storefront offices.